/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate licenses this file
 * to you under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.expression.scalar.string;

import io.crate.expression.scalar.ScalarFunctionModule;
import io.crate.expression.scalar.UnaryScalar;
import io.crate.metadata.functions.Signature;
import io.crate.types.DataTypes;

public final class InitCapFunction {

    public static void register(ScalarFunctionModule module) {
        module.register(
            Signature.scalar(
                "initcap",
                DataTypes.STRING.getTypeSignature(),
                DataTypes.STRING.getTypeSignature()
            ),
            (signature, boundSignature) ->
                new UnaryScalar<>(
                    signature,
                    boundSignature,
                    DataTypes.STRING,
                    InitCapFunction::toCapital
                )
        );
    }

    private static String toCapital(String val) {
        if (val.length() == 0) {
            return val;
        }

        char[] chars = new char[val.length()];
        boolean wordStarts = true;
        for (int cp, i = 0, j = 0; i < val.length(); i += Character.charCount(cp)) {
            cp = val.codePointAt(i);

            if (Character.isSpaceChar(cp)) {
                chars[j++] = val.charAt(i);
                wordStarts = true;
                continue;
            }

            if (wordStarts) {
                chars[j++] = (char) Character.toUpperCase(cp);
                wordStarts = false;
            } else {
                chars[j++] = (char) Character.toLowerCase(cp);
            }
        }

        return new String(chars);
    }
}

